Rex:

> Yes, friend, you're in the right place.  However, you may be wise to ignore,
> rather than becoming upset by, requests for proof---particularly when you're
> expressing an opinion.  OTOH, you may want to provide background references to
> those who politely do the same for you.

Thanks. I appreciate that you're one of the people on this list that
actually respects my opinions, without getting peeved.

Here are some more opinions of mine (cooked foodists take note).

Wes

--
Mutat Res 1997 May 12;376(1-2):129-34

Analysis of cooked muscle meats for heterocyclic aromatic amine
carcinogens.

Knize MG, Salmon CP, Mehta SS, Felton JS

Biology and Biotechnology Research Program, Lawrence Livermore National
Laboratory, Livermore, CA 94550, USA.

A number of related heterocyclic amines that are mutagenic in bacterial
test systems and carcinogenic in animals are formed during the cooking
of food. The most commonly reported and abundant compounds are PhIP,
MeIQx, DiMeIQx, IQ and A alpha C. Using analysis by solid-phase
extraction and HPLC, amounts found in foods range from less than one
ng/g for products from fast-food restaurants, up to 14 ng/g in
commercially cooked products and over 300 ng/g for well done
flame-grilled chicken breast meat. Interestingly, marinating meat for 4
h greatly reduces the amount of PhIP produced during cooking, but not
MeIQx. Comparing mutagenic activity in meat samples to the mutagenic
activity accounted for by the known heterocyclic amines shows that most
samples have activity that cannot be accounted for by the aromatic
amines we can currently identify. This suggests
that additional compounds are present in these foods and need to be
investigated, particularly those grilled over open flames.
--
Cancer Lett 1997 Mar 19;114(1-2):89-90

Cooked casein promotes colon cancer in rats, may be because of mucosal
abrasion.

Corpet DE, Chatelin-Pirot V

Ecole Nationale Veterinaire, Laboratoire de Securite des
Alimentes,Institut National de la Recherche Agronomique, Toulouse,
France.
--
Environ Health Perspect 1994 Oct;102 Suppl 6:201-4

Mutagenic activity of heterocyclic amines in cooked foods.

Felton JS, Knize MG, Dolbeare FA, Wu R

Biology and Biotechnology Research Program, Lawrence Livermore National
Laboratory, California.

Mutagenic heterocyclic amines are generated in foods when they are
cooked at temperatures over 150 degrees C. These compounds are present
from 0.1 to 50 ppb, depending on the food and cooking conditions. These
heterocyclic amines are not only present in cooked red meat, fish, and
chicken, but are also present at lower levels in baked and fried foods
derived from grain. Mutagenicity of fried beef hamburgers cooked at 230
degrees C is 800 +/- 37 TA98 revertants per gram cooked weight. We
measured  2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MelQx),
2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMelQx), and
2-amino-3-methylimidazo[4,5-f]quinoline (IQ) formation at this
temperature and found 3.0 +/- 2.0, 1.0 +/- 0.18, and 0.06 +/- 0.03 ng/g,
respectively. 2-amino-1-methyl-6-phenylimidaz[4,5-b]pyridine (PhIP) was
found at a higher concentration of 9.6 ng/g. In our laboratory we have
shown these heterocyclic amines are capable of producing both reverse
and forward mutations in Salmonella bacteria and forward mutations in
Chinese hamster ovary cells (CHO). We have also been able to show a
statistically significant increase in mutations in the pancreas of the
"mutamouse" following PhIP exposure. The pancreas also shows relatively
high DNA binding compared to other organs in the mouse. The number and
type of mutations depend on the repair capacity of the cells for both
Salmonella and CHO. In Salmonella the mutations are primarily 2-base
deletions when the cells lack uvrB repair, but mutations are more
complex (larger deletions and insertions)
but lower in frequency when repair is functional.
--
Carcinogenesis 1995 Jan;16(1):39-52

Cancer risk of heterocyclic amines in cooked foods: an analysis and
implications for research.

Layton DW, Bogen KT, Knize MG, Hatch FT, Johnson VM, Felton JS

Health and Ecological Assessment Division, Lawrence Livermore National
Laboratory, University of California, Livermore 94550.

Heterocyclic amines (HAs) are formed as pyrolysis products during the
cooking of meats/fish. These substances are potent mutagens in the
Ames/Salmonella assay and are also carcinogens in laboratory animals. In
order to assess the magnitude of the cancer risk posed by their presence
in the US diet, we estimated the average intakes of HAs, based on
analyses of the concentrations of HAs in cooked foods and data from a
dietary survey of the US population and quantified the cancer potencies
of the individual compounds using dose-response data from animal
bioassays. Measured concentrations of HAs in cooked foods were taken
from a major review of the open literature. Only those concentrations
that were associated with normal cooking conditions were chosen for use
in estimating dietary intakes. The average consumption of HA-bearing
foods was determined by analyzing statistically the intakes of 3563
individuals who provided 3 day dietary records in a USDA sponsored
random survey of the US population during 1989. Dietary intakes of the
five principal HAs in descending order were
2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) >
2-amino-9H-pyrido[2,3-b]indole (A alpha C) >
2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) >
2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx) >
2-amino-3-methylimidazo[4,5-f]quinoline (IQ).
The carcinogenic potencies, in contrast, were almost the reverse order:
IQ > DiMeIQx > MeIQx > PhIP > A alpha C. An upper-bound estimate of the
incremental cancer risk is 1.1 x 10(-4), using cancer potencies based on
a body surface area basis. Nearly half (46%) of the incremental risk was
due to ingestion of PhIP. Consumption
of meat and fish products contributed the most (approximately 80%) to
total risk.
--
Environ Health Perspect 1993 Mar;99:129-34

Exposure to heterocyclic amines.

Wakabayashi K, Ushiyama H, Takahashi M, Nukaya H, Kim SB, Hirose M,
Ochiai M, Sugimura T, Nagao M

Carcinogenesis Division, National Cancer Center Research Institute,
Tokyo, Japan.

Many mutagenic heterocyclic amines (HAs) have been isolated from cooked
foods and pyrolysates of amino acids and proteins, and the
carcinogenicity of 10 of these HAs in rodents and of 1 in monkeys has
been reported. Quantification of these carcinogenic HAs in various kinds
of cooked foods indicated that the level of
2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) was highest
(0.56-69.2 ng/g), that of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline
(MeIQx) was second highest (0.64-6.44 ng/g), and those of other HAs were
0.03-2.50 ng/g. Heterocyclic amines were found in urine samples of 10
healthy volunteers consuming a normal diet, but HAs were not detectable
in urine samples of three patients receiving parenteral alimentation.
These results strongly suggest that humans are continuously exposed to
HAs derived from food in the normal diet. Based on quantitative data on
the levels of HAs in cooked foods and urine samples, the daily exposures
to PhIP and MeIQx were estimated to be 0.1-13.8 micrograms and 0.2-2.6
micrograms per person, respectively. These levels of carcinogenic HAs
are in the same range as those of other carcinogens such as
N-nitrosodimethylamine and benzo[a]pyrene to which humans are exposed.
--
Mutat Res 1984 Nov-Dec;141(3-4):131-4

Occurrence of mutagens in canned foods.

Krone CA, Iwaoka WT

Mutagens are shown to be present in a variety of commercially
heat-processed foods. Since these substances are not present in the
unheated raw material, it appears that they are produced during
processing. Canned salmon and beef broth showed the highest mutagenicity
while other canned beef and fish products yielded lower but detectable
levels. These findings are significant not only because of the large
proportion of the food supply which is processed by canning, but also
because the mutagens in these foods exhibit chemical behaviors and
Salmonella strain specificity similar to mutagens in grilled foods which
have been shown to be mammalian carcinogens.
--
Food Addit Contam 1987 Jan-Mar;4(1):27-36

The formation and occurrence of amino acid pyrolysates and related
mutagens in cooked foods.

Massey RC, Dennis MJ

The classes of cooked foods that contain detectable levels of mutagenic
activity are discussed together with the effects of different cooking
procedures on the extent of mutagen formation. Analytical procedures
that have so far been devised to quantify the concentrations of specific
mutagenic compounds are described and the levels of these species that
have been detected in cooked foods are detailed.
--
Cancer Res 1992 Apr 1;52(7 Suppl):2092s-2098s

Food-derived mutagens and carcinogens.

Wakabayashi K, Nagao M, Esumi H, Sugimura T

National Cancer Center Research Institute, Tokyo, Japan.

Cooked food contains a variety of mutagenic heterocyclic amines. All the
mutagenic heterocyclic amines tested were carcinogenic in rodents when
given in the diet at 0.01-0.08%. Most of them induced cancer in the
liver
and in other organs. It is noteworthy that the most abundant
heterocyclic amine in cooked food,
2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine, produced colon and
mammary carcinomas in rats and lymphomas
in mice but no hepatomas in either.
2-Amino-3-methylimidazo[4,5-f]quinoline induced liver cancer in monkeys.
Formation of adducts with guanine by heterocyclic amines is presumably
involved in their carcinogenesis. Quantification of heterocyclic amines
in cooked foods and in human urine indicated that humans are
continuously exposed to low levels of them in the diet. These low levels
of heterocyclic amines are probably insufficient to produce human
cancers by themselves. However, a linear relationship between DNA adduct
levels and a wide range of doses of a heterocyclic amine was
demonstrated in animals. It suggests that even very low doses of
heterocyclic amines form DNA adducts and may be implicated in the
development of human cancer under conditions in which many other
mutagens-carcinogens, tumor promoters, and factors stimulating cancer
progression exist.
--
Adv Exp Med Biol 1991;289:115-31

An experimental approach to identifying the genotoxic risk by cooked
meat mutagens.

Loprieno N, Boncristiani G, Loprieno G

Dipartimento di Scienze dell'Ambiente e del Territorio dell'Universita
di Pisa, Italy.

In order to define the toxicological risk for the human population
derived from the chemical compounds formed during the process of cooking
animal meat, which have been described to possess a mutagenic,
genotoxic, and carcinogenic activity, an extensive study has been
developed on cooked meat extract and two cooked meat mutagens, IQ and
MeIQx. The study has been based on toxicokinetics and mouse tissue
distribution of the two chemicals, on in vitro and in vivo
mutagenicity/genotoxicity analyses (gene mutation, chromosome
aberration, micronuclea in mouse bone marrow cells, mice urine and
faeces mutagenicity test), as well as in vivo protein and DNA binding.
The two chemicals have been found positive for the induction of gene
mutation on Salmonella, but not in V-79 Chinese hamster cells; IQ only
has been found positive for the induction of chromosome aberrations on
CHO cells and cultured human lymphocytes. IQ and MeIQx were negative for
the induction of micronuclea in mice treated with 40 mg/kg of the
chemicals; the lowest effective administered dose to the mice which
produced mutagenic urine was 0.4 mg/kg of IQ and 0.04 mg/kg of MeIQx. A
dose of 40 mg/kg of IQ given by gavage to mice produced an excretion of
1-4% of the applied dose in the urine and 0.1-2% of the applied dose
in the faeces, when evaluated chemically or mutagenically. The DNA
adducts for the liver were correlated with the dose of the IQ and MeIQx
administered to the mice. All the data have been used for defining a
possible
risk estimate derived to the human population as a consequence of a
cooked meat diet.
--